The invention relates to a method for controlling a trajectory planning process of a vehicle, in particular an ego-vehicle. The invention also relates to a computer program product, a device and a vehicle equipped with the device for controlling a trajectory planning process of an ego-vehicle.
Future driver assistance systems can provide a driver with greater assistance than current rule-based systems by exactly planning the trajectory to be traveled. Current control-oriented solutions of an active cruise control system of vehicles usually use only one controller which can be parameterized differently depending on a situation. For highly automated driving functions, it may be absolutely necessary to exactly plan the trajectory to be traveled. However, a process of planning a convenient trajectory which can be implemented by the vehicle may be associated with considerable computational complexity. The computational complexity may be considerably increased further if, for example, trajectories for different travel modes have to the calculated and evaluated by the trajectory planning process. This computational complexity may be so high that the trajectory cannot be calculated in control devices of the vehicle or can be calculated only with a considerable delay.
Therefore, an object of the invention is to efficiently improve control of a trajectory planning process of a vehicle, in particular an ego-vehicle.
According to one aspect, the invention is distinguished by a method for controlling a trajectory planning process of a vehicle, in particular an ego-vehicle. The method comprises determining a longitudinal movement of the ego-vehicle, the longitudinal movement including a speed of the ego-vehicle. The method also comprises determining a longitudinal movement of an object, the longitudinal movement including a speed of the object. The object is preferably a vehicle, for example a motor vehicle or a motorcycle. The method comprises calculating a target trajectory of the object on the basis of a predicted trajectory of the object. A predicted trajectory is a trajectory which is predetermined or precalculated using a movement model of the object, for example. For this purpose, it is possible to make assumptions with regard to an acceleration, a speed and/or a position of the object. A target trajectory may comprise, for example, a safety distance which must be complied with between the object and the ego-vehicle at the end of a maneuver, in particular a predefined maneuver. The method also comprises calculating an end time of a maneuver of the ego-vehicle, the end time of the maneuver being a time at which a differential speed between the ego-vehicle and the object has decreased. The method comprises calculating a distance between a position of the ego-vehicle and a position of the third-party vehicle with respect to the calculated target trajectory at the calculated end time of the maneuver of the ego-vehicle, and, if the calculated distance of the ego-vehicle at the calculated end time of the maneuver is equal to a predefined threshold value or undershoots a predefined threshold value, setting the determined speed of the object as the target speed of the ego-vehicle, and transferring or transmitting the target speed to a trajectory planning process for calculating a follow-on travel trajectory for the ego-vehicle. The predefined threshold value may be a predefined safety distance. The predefined safety distance may be dynamic and/or static. For example, the predefined safety distance may be determined on the basis of the speed of the object and/or of the ego-vehicle. The threshold value may be determined by use of a hysteresis function, in particular by a hysteresis function of the safety distance. Calculating the predefined threshold value by use of a hysteresis function can prevent continuous toggling between free travel and follow-on travel. As a result, the ego-vehicle can be controlled with a greater degree of convenience.
Determining an end time and calculating a distance at the determined end time advantageously make it possible to efficiently determine whether the ego-vehicle can carry out a maneuver in free travel or in follow-on travel. If the distance at the end time is equal to a predefined threshold value or undershoots a predefined threshold value, the target speed of the ego-vehicle can be selected only up to at most the speed of the object in order to prevent a safety distance from being undershot and/or to prevent a collision with an object moving in front of the ego-vehicle, for example. In the event of a calculated distance which is equal to a predefined threshold value or undershoots a predefined threshold value, the ego-vehicle can change over from a free travel mode to a follow-on travel mode at the current time. The ego-vehicle can therefore predictively anticipate a possible future movement of the object in the longitudinal direction already at the current time and can react accordingly, for example by selecting the speed of the object as the target speed. A follow-on travel mode of the ego-vehicle can be efficiently and predictively recognized. The trajectory planning process can therefore be efficiently controlled by being able to plan one or more follow-on travel trajectories at the determined target speed. Further trajectories, in particular free travel trajectories, need not be calculated by the trajectory planning process since it was determined, before starting the trajectory planning process, that the ego-vehicle is in a follow-on travel mode.
According to one advantageous configuration, the predicted trajectory can be determined on the basis of a predefined movement model of the object on the basis of the determined longitudinal movement of the object, and/or the target trajectory can take into account a safety distance to the object, and/or the predefined threshold value can correspond to the safety distance. The predefined movement model makes it possible to efficiently calculate a future behavior of the object in the longitudinal direction. Furthermore, taking a safety distance into account makes it possible to directly include the safety parameters which are conventional in road traffic in the control of the trajectory planning process of the vehicle.
According to another advantageous configuration, the end time of the maneuver can be calculated on the basis of a movement model of the object and a movement model for the ego-vehicle. Using movement models makes it possible to efficiently determine or calculate a future behavior of the ego-vehicle and of the object.
According to another advantageous configuration, the movement model of the object can keep an acceleration of the object constant until a predefined time and can set the acceleration to zero after the predefined time. Furthermore, the movement model of the ego-vehicle can keep a predefined average acceleration of the ego-vehicle until the end time of the maneuver. This makes it possible to calculate a future acceleration behavior for the object and the ego-vehicle with little computational complexity.
According to another advantageous configuration, the position of the ego-vehicle can be calculated by way of the movement model of the ego-vehicle on the basis of the determined longitudinal movement of the ego-vehicle at the end time of the maneuver. Furthermore, the position of the object can be calculated by way of the movement model of the object on the basis of the determined longitudinal movement of the object at the end time of the maneuver. On the basis of the current longitudinal movement of the ego-vehicle and of the object, the position and therefore also the distance at the end time of the maneuver between the ego-vehicle and the object can hereby be easily calculated.
According to another advantageous configuration, the method may comprise receiving a desired speed of the ego-vehicle, and/or, if the desired speed of the ego-vehicle is less than the speed of the object and/or the calculated distance of the ego-vehicle at the calculated end time of the maneuver exceeds a predefined threshold value, for example a predefined safety distance, setting the desired speed as the target speed of the ego-vehicle, and/or, if the desired speed of the ego-vehicle is greater than or equal to the speed of the object and/or the calculated distance of the ego-vehicle at the calculated end time of the maneuver is equal to a predefined threshold value or undershoots a predefined threshold value, setting the speed of the object as the target speed of the ego-vehicle. This makes it possible to efficiently determine free travel or a free travel mode and/or follow-on travel or a follow-on travel mode of the ego-vehicle.
According to another advantageous configuration, the method may also comprise transferring the target speed to a trajectory planning process for calculating a follow-on travel trajectory for the ego-vehicle if the calculated distance of the ego-vehicle at the calculated end time of the maneuver is equal to a predefined threshold value or undershoots a predefined threshold value, and/or transferring the target speed to a trajectory planning process for calculating a free travel trajectory for the ego-vehicle if the desired speed of the ego-vehicle is less than the speed of the object or the calculated distance of the ego-vehicle at the calculated end time of the maneuver exceeds a predefined threshold value. This makes it possible to efficiently control a trajectory planning process. In particular, free travel and the trajectory planning process for free travel can be efficiently determined. As a result, it may no longer be necessary to plan trajectories for both travel modes, free travel and follow-on travel. Consequently, the trajectory planning process can plan the trajectories for only free travel or follow-on travel of the ego-vehicle in a control device in a resource-efficient manner.
According to another aspect, the invention is distinguished by a computer program product for controlling a trajectory planning process of an ego-vehicle, wherein the computer program product comprises instructions which, when executed on a control device or a computer of the ego-vehicle, carry out the method described above.
According to another aspect, the invention is distinguished by a device for controlling a trajectory planning process of an ego-vehicle, wherein the device is designed to carry out the method described above.
According to another aspect, the invention is distinguished by a vehicle equipped with a device for controlling a trajectory planning process of an ego-vehicle, wherein the device is designed to carry out the method described above.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
One preferred exemplary embodiment of the invention is described below on the basis of the accompanying drawings.